U.S. patent number 6,183,060 [Application Number 09/116,905] was granted by the patent office on 2001-02-06 for ink jet recorder.
This patent grant is currently assigned to Brother Kogyo Kabushiki Kaisha. Invention is credited to Hiroshi Tokuda.
United States Patent |
6,183,060 |
Tokuda |
February 6, 2001 |
Ink jet recorder
Abstract
An ink-jet recording apparatus includes a head for ejecting ink
and a carriage for conveying the head. When the cartridge has moved
to a maintenance area and rotates a lever, the rotational force is
transformed into a force for causing a pressing plate supporting a
strip to move against the nozzle, by means of bevel gears, a
pressing piece and a pivot arm. The strip comes in contact with the
nozzle surface to wipe ink. The recording apparatus has a pump for
applying a pressure to the interior of the head for purging the
head and a conveyer for conveying the strip to refresh the part of
the strip opposing the head. The pump and conveyer can be driven by
a common motor which is also used for conveying the recording
medium. The driving source used for the recording apparatus is
shared thus making it possible to achieve a simplified
configuration of the recording apparatus.
Inventors: |
Tokuda; Hiroshi (Anjou,
JP) |
Assignee: |
Brother Kogyo Kabushiki Kaisha
(Nagoya, JP)
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Family
ID: |
26508552 |
Appl.
No.: |
09/116,905 |
Filed: |
July 17, 1998 |
Foreign Application Priority Data
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Jul 18, 1997 [JP] |
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9-194529 |
Jul 18, 1997 [JP] |
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9-194531 |
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Current U.S.
Class: |
347/33; 347/29;
347/88 |
Current CPC
Class: |
B41J
2/16535 (20130101) |
Current International
Class: |
B41J
2/165 (20060101); B41J 002/165 () |
Field of
Search: |
;347/29,33,88,30 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4-141439 |
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May 1992 |
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JP |
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40564895 |
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Mar 1993 |
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JP |
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5-193152 |
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Aug 1993 |
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JP |
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8-305325 |
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Nov 1996 |
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JP |
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8-323999 |
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Dec 1996 |
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JP |
|
9-141898 |
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Jun 1997 |
|
JP |
|
Primary Examiner: Le; N.
Assistant Examiner: Hsieh; Shih-wen
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. An ink-jet recording apparatus comprising:
a recording head having a nozzle for ejecting ink;
a carriage for conveying the recording head and moving across the
width of the recording area opposing a recording medium and an
additional area outside thereof;
a moving element, disposed within the area outside the recording
area, which moves by being put in contact with the carriage or the
head when the carriage has moved to the outside area;
a strip disposed within the outside area for cleaning the recording
head with a surface thereof; and
a support element for supporting the rearside of the strip and
moving toward the recording head to press the strip against the
nozzle of the recording head, wherein the support element is caused
to move toward the head by a driving force generated by the
movement of the moving element, to thereby press the strip against
the head.
2. The ink-jet recording apparatus according to claim 1, further
comprising a transmission element for transmitting the force
generated by the movement of the moving element to the support
element.
3. The ink-jet recording apparatus according to claim 1, wherein
the moving element is a rotational lever which is rotated by being
put into contact with the carriage or the head when the carriage
has moved to the area outside the recording area.
4. The ink-jet recording apparatus according to claim 3, further
comprising:
a first gear connected to the rotational lever;
a second gear meshing with the first gear;
a rotational element connected to the second gear; and
a pivot arm urged by the rotational element so as to pivot, the
pivot arm being engaged with the support element, thereby
transmitting the rotational force of the rotational lever to the
support element so that the support element will move toward the
head.
5. The ink-jet recording apparatus according to claim 4, wherein
the pivot arm comprises:
an upper arm;
a lower arm;
a rotational shaft for rotatably supporting the lower arm with
respect to the upper arm; and
a spring urging the lower arm in a predetermined rotational
direction with respect to the upper arm, the upper arm has a pivot
axle for the pivot arm, the lower arm is engaged with the support
element, and the lower arm rotates with respect to the upper arm,
opposing the urging force of the spring, when the support element
has pressed the strip against the head.
6. The ink-jet recording apparatus according to claim 1, further
comprising: a damper for damping the impacts when the support
element has presses the strip against the head.
7. The ink-jet recording apparatus according to claim 1, wherein an
elastic element is provided on the support surface of the support
element.
8. The ink-jet recording apparatus according to claim 1, wherein at
least two ribs are formed on a support surface of the support
element and a part of the strip is stretched between the ribs.
9. The ink-jet recording apparatus according to claim 1, further
comprising: a conveyer for conveying the strip relative to the head
to refresh the part of the strip opposing the head.
10. The ink-jet recording apparatus according to claim 9, further
comprising:
a pump which is coupled to the recording head, and applies a
pressure to the interior of the recording head to purge ink
channels and the nozzle; and
a driving motor with a conveying roller for conveying the recording
media,
wherein the pump and the conveyer are also driven by a driving
force from the driving motor.
11. An ink-jet recording apparatus comprising:
a recording head having ink channels formed therein and a nozzle
for ejecting ink;
a pump which applies a pressure to the interior of the recording
head to purge the ink channels and the nozzle;
a strip used for cleaning the recording head;
a conveyer for conveying the strip to thereby refresh a part of the
strip opposing the nozzle; and
a common driving source for driving the pump and the conveyer.
12. The ink-jet recording apparatus according to claim 11, further
comprising: a carriage for conveying the recording head, capable of
moving across the width of the recording area opposing a recording
medium and an additional area outside thereof where the strip and
the conveyer are disposed.
13. The ink-jet recording apparatus according to claim 12, wherein
the recording head is provided with a hole which communicates with
the ink channels and is connected to the pump.
14. The ink-jet recording apparatus according to claim 13, wherein
when the carriage has moved to the area outside the recording area,
the hole is covered by a cap communicating with the pump so that
pressurized air is supplied from the pump through the cap into the
interior of the recording head, to thereby effect the purging.
15. The ink-jet recording apparatus according to claim 12, further
comprising:
a conveying roller for conveying the recording medium; and
a motor for rotating the conveying roller,
wherein the motor is a common driving source for driving the pump
and the conveyer.
16. The ink-jet recording apparatus according to claim 15, further
comprising:
a planetary gear mechanism which can transmit the driving force
from the motor to the pump and the conveyer only when the conveying
roller is reversed.
17. The ink-jet recording apparatus according to claim 16, further
comprising:
a rotational lever which is rotated by being put in contact with
the carriage or the head when the carriage has moved to the area
outside the recording area;
a pivot arm pivoting from a first position to a second position
with the rotation of the rotational lever, wherein the planetary
gear mechanism has a sun gear, a planetary gear and a planetary arm
supporting the planetary gear, and when the pivot arm is positioned
at the first position, the pivot arm interferes with the rotation
of the planetary arm even if the conveying roller is reversed,
whereas when the pivot arm is positioned at the second position,
the planetary gear mechanism transmits the driving force of the
motor to the pump and the conveyer in the case where the conveying
roller is reversed.
18. The ink-jet recording apparatus according to claim 11, wherein
the pump comprises:
a pair of pistons each having an individual piston pin;
a single cylinder, having an intake port and exhaust port, inside
which the two pistons move; and
a cam having a pair of eccentric annular grooves which are engaged
with the two piston pins, respectively.
19. The ink-jet recording apparatus according to claim 11, wherein
the conveyer comprises:
a feed roller for delivering the strip; and
a winding shaft for taking up the strip.
20. The ink-jet recording apparatus according to claim 19, wherein
the feed roller is a fixed-rate feed roller.
21. The ink-jet recording apparatus according to claim 19, wherein
the winding shaft has a slip clutch.
22. The ink-jet recording apparatus according to claim 11, wherein
the strip is accommodated in a cassette casing which is removably
attached to the recording apparatus.
23. The ink-jet recording apparatus according to claim 11, wherein
the driving source drives the pump and the conveyer
simultaneously.
24. The ink-jet recording apparat us according to claim 11, which
is a hot-melt type ink-jet printer.
25. A maintenance device for an ink-jet recording apparatus having
a recording head having ink channels formed therein and a nozzle
for ejecting ink, comprising:
a pump which is connected to the recording head and applies a
pressure to the interior of the recording head to purge the ink
channels and the nozzle;
a strip used for cleaning the recording head;
a conveyer for conveying the strip to thereby refresh a part of the
strip opposing the nozzle; and
a common driving source for driving the pump and the conveyer.
26. The maintenance device according to claim 25, wherein the pump
applies a positive pressure inside the recording head.
27. The maintenance device according to claim 25, wherein the pump
comprises:
a pair of pistons each having an individual piston pin;
a single cylinder, having an intake port and exhaust port, inside
which the two pistons move; and
a cam having a pair of eccentric annular grooves which are engaged
with the two piston pins, respectively.
28. The maintenance device according to claim 25, wherein the
conveyer comprises:
a feed roller for delivering the strip; and
a winding shaft for taking up the strip.
29. The maintenance device according to claim 25, wherein the
winding shaft has a slip clutch.
30. The maintenance device according to claim 25, wherein the feed
roller is a fixed-rate feed roller.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet printer including a
maintenance mechanism for keeping a good ejection condition of the
ink-jet head, and more specifically relates to an ink-jet printer
including a maintenance mechanism using strip-like cleaning paper
for receiving ejected ink from the head and/or wiping the nozzle
surface.
2. Description of the Related Art
Conventional ink-jet printers have an ink-jet head for ejecting
ink, a carriage for moving the head along a recording medium in
order to eject ink at a desired position of the recording medium,
and a maintenance mechanism for keeping a good ejection condition
of the ink-jet head.
For example, U.S. Pat. No. 5,177,505 corresponding to Japanese
Patent Application Laid-Open No. 4-141,439 discloses a maintenance
mechanism in which cleaning of an ink-jet head is performed by
pressing the head against paper on a platen and frictionally
sliding the head relative to the paper.
Japanese Patent Application Laid-Open No. 8-323,999 discloses a
maintenance unit for an ink-jet printer using hot-melt type ink.
This maintenance unit has an ink wiping mechanism wherein a strip
of maintenance paper spooled out from a supply spool is put in
contact with the head to thereby wipe ink.
Japanese Patent Application Laid-Open No. 9-141,898 (corresponding
to U.S. patent application Ser. No. 08/751,768) discloses a
cleaning device which, in order to remove dust and air remaining in
the a nozzle of the ink-jet head, forces ink to eject out from the
nozzle to thereby collect the dust etc., on cleaning paper disposed
marginally spaced away from the nozzle. The ink-jet printer
disclosed in Japanese Patent Application Laid-Open No. 9-141,898,
comprises a pump which may apply either a positive back pressure or
negative pressure to the ink-jet head, a conveyer having a strip of
cleaning paper and conveying it to the head and a pushing means for
pushing the cleaning paper against the head. However, an ink-jet
printer of this type, was provided with a dedicated motor or
solenoid as the driving source for the means of pushing the
cleaning paper. Further, separate driving sources were used to
drive the pump and the conveying means for the cleaning paper. In
short, driving of the maintenance mechanism needed a multiple
number of driving sources, resulting in a complicated
configuration. Moreover, an ink-jet printer needs driving sources
such as one as a feed motor for feeding print sheets and one for
the carriage. Thus, an ink-jet printer needs a number of driving
sources, resulting in a complex configuration and producing
difficulties in reduction of the manufacturing cost.
SUMMARY OF THE INVENTION
A first object of the invention is to provide an ink-jet recording
apparatus having a mechanism which can move the strip to be used
for maintaining the head toward the head, without using a special
actuator such a motor, solenoid or the like.
A second object of the invention is to provide a maintenance device
which can drive a pump and a strip-conveyer used for maintaining
the ink-jet head with a lower number of driving sources as well as
to provide an ink-jet recording apparatus having the maintenance
device.
In accordance with the first aspect of the invention, an ink-jet
recording apparatus is provided which comprises:
a recording head having a nozzle for ejecting ink;
a carriage for conveying the recording head and moving across the
width of the recording area opposing a recording medium and an
additional area outside thereof;
a moving element which is disposed within the area outside the
recording area and is capable of moving by being put in contact
with the carriage or the head when the carriage has moved to the
outside area;
a strip disposed within the outside area for cleaning the recording
head with the surface thereof; and
a support element for supporting the rearside of the strip, which
can move toward the recording head to press the strip against the
nozzle of the recording head, wherein the support element is caused
to move toward the head by the driving force generated by the
movement of the moving element, to thereby press the strip against
the head.
In accordance with the ink-jet recording apparatus of the
invention, when the carriage having the head therein has moved to
the area outside the recording area, for example to the position
opposing the strip in the maintenance area, the moving element,
e.g., a rotational lever is pressed by the head or the carriage and
moved. A force generated when the moving element is moved, for
example, a rotational force can be used for the power source for
causing the support element, e.g., a pressing plate, to move the
strip toward the head. Accordingly, in the present invention, there
no need to provide any dedicated actuator for moving the support
element, thus simplifying the configuration of the maintenance
mechanism, and hence reducing the manufacturing cost of the ink-jet
printer.
In this document, it should be noted that cleaning of the recording
head with a strip, includes not only wiping the ink adhering to the
head by pressing the strip against the recording head, but also the
cleaning of the ink channels and the nozzle by ejecting ink toward
the strip.
The ink-jet recording apparatus may further comprise transmission
elements for transmitting the force generated by the movement of
the moving element to the support element. When the moving element
is a rotational lever, the transmission elements may comprise: a
first gear connected to the rotational lever; a second gear meshing
with the first gear; a rotational element connected to the second
gear; and a pivot arm urged by the rotational element so as to
pivot. The pivot arm may be engaged with the support element. The
pivot arm may comprise: an upper arm; a lower arm; a rotational
shaft for rotatably supporting the lower arm with respect to the
upper arm; and a spring urging the lower arm in the predetermined
rotational direction with respect to the upper arm. The upper arm
may have a pivot axle for the pivot arm, the lower arm may be
engaged with the support element, and the lower arm may rotate with
respect to the upper arm, opposing the urging force of the spring,
when the support element has pressed the strip against the
head.
Further, the ink-jet recording apparatus may further comprise: a
damper for damping the impacts when the support element has pressed
the strip against the head. The damper beneficially protects the
head from impacts and can absorb the error and fluctuations
occurring from the support element of the strip during manufacture
and/or assembly. Therefore, it is possible to further enhance the
durability of the head and the productivity of the ink-jet
recording apparatus. The aforementioned lower arm and the spring
may function as a damper for damping the impacts arising when the
support element presses the strip against the head. Further, an
elastic element may be provided on the support surface of the
support element, to provide the functionality of a damper.
In accordance with the second aspect of the invention, an ink-jet
recording apparatus is provided which comprises:
a recording head having ink channels formed therein and a nozzle
for ejecting ink;
a pump which applies a pressure to the interior of the recording
head to purge the ink channels and the nozzle;
a strip used for cleaning the recording head;
a conveyer for conveying the strip to thereby refresh the part of
the strip opposing the nozzle; and
a common driving source for driving the pump and the conveyer.
In the ink-jet recording apparatus in accordance with the second
aspect thus configured, since the pump and the conveyer is driven
by the common driving source, the number of the driving sources in
the recording apparatus can be reduced to realize a very simplified
configuration, and hence it is possible to reduce the manufacturing
cost of the ink-jet recording apparatus.
The ink-jet recording apparatus of the second aspect may further
comprise a carriage for conveying the recording head. The recording
head may be provided with a hole which communicates with the ink
channels and which can be connected to the pump. When the carriage
has moved to the area outside the recording area, the hole may be
covered by a cap communicating with the pump so that pressurized
air may be supplied from the pump through the cap into the interior
of the recording head, to thereby effect the purging. This
application of pressurized air (positive pressure) can forcibly
eject the ink together with dust and air bubbles from the ink
channels and the interior of the nozzle. Since the strip is
disposed opposite the head upon the ejection, the forcibly ejected
ink can be beneficially received by the strip. As a method for
forcing the ink to be ejected, a negative pressure may also be
applied from the exit side (e.g. nozzle) of the ejection of ink
path, but the method of applying a positive pressure is
advantageous because the strip does not need to be removed from the
front side of the head.
When the ink-jet recording apparatus comprises: a conveying roller
for conveying the recording medium; and a motor for rotating the
conveying roller, the motor may be used as a common driving source
for driving the pump and the conveyer. This configuration enables
the sharing of a driving source of the recording apparatus, thus
making it possible to reduce the cost. In this case, the apparatus
may further comprise: a planetary gear mechanism which can transmit
the driving force from the motor to the pump and the conveyer only
when the conveying roller is reversed. This configuration enables
selective use of the driving force in accordance with the
rotational direction of the conveying roller.
The pump may comprise: a pair of pistons each having an individual
piston pin; a single cylinder, having an intake port and exhaust
port, inside which the two pistons move; and a cam having a pair of
eccentric annular grooves which are engaged with the two piston
pins, respectively. The motor's driving force can be transmitted to
the cam by way of a plurality of gears and a planetary gear
mechanism. The conveyer may comprise: a feed roller for delivering
the strip; and a shaft for taking up the strip. The driving force
from the motor can be transmitted to the feed roller and the shaft
for taking up the strip by way of a gear attached thereto or
integrated therewith, another gear and a planetary gear
mechanism.
When a positive pressure (back pressure) is applied from the pump
and the ink ejected thereby is received by the strip, it is
necessary to synchronize the operation of the pump with the
conveyer. That is, since the ejected amount of ink varies in
accordance with the amount of pressure from the pump, it is
necessary to vary the conveyed length of the strip in accordance
with the ejected amount in order to further enhance the reception
of ink. In the present invention, since the pump and conveyer are
driven by the common driving source, it is possible to drive them
both in synchronism in a very simple manner. Accordingly, it is no
longer necessary to independently control the driving timing and
driven amount of them both.
In accordance with the third aspect of the invention, a maintenance
device for an ink-jet recording apparatus having a recording head
having ink channels formed therein and a nozzle for ejecting ink,
is provided. This maintenance device comprises:
a pump which is connected to the recording head and applies a
pressure to the interior of the recording head to purge the ink
channels and the nozzle;
a strip used for cleaning the recording head;
a conveyer for conveying the strip to thereby refresh a part of the
strip opposing the nozzle; and
a common driving source for driving the pump and the conveyer.
Since this maintenance device uses a single, common driving source
for driving the pump and the conveyer, it is possible to simplify
the configuration of the maintenance device as well as that of the
ink-jet recording apparatus to which the maintenance device is
applied, thus making it possible to reduce the manufacturing
cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall view showing the essential configuration of an
ink-jet printer in accordance with the present invention;
FIG. 2 is an exploded perspective view showing the configuration of
the head of an ink-jet printer;
FIG. 3 is a top view showing the configuration of the ink tank of
the head shown in FIG. 2;
FIGS. 4A and 4B are sectional views cut across lines B--B and C--C,
respectively for illustrating the configuration of the ink tank
shown in FIG. 3;
FIG. 5 is a left-side view showing the configuration of a cassette
for head maintenance used in the ink-jet printer in accordance with
an embodiment;
FIG. 6 is a vertical sectional view showing the configuration of
the cassette shown in FIG. 5;
FIG. 7 is a front view showing the configuration of a maintenance
unit when the cassette is mounted;
FIG. 8 is a sectional view cut across a line D--D showing the
maintenance unit shown in FIG. 7;
FIG. 9 is a left-side view showing the maintenance unit shown in
FIG. 7;
FIG. 10 is a right-side view showing the configuration in the
vicinity of a pump for the maintenance unit;
FIG. 11 is an illustrative view showing a wiping operation of the
maintenance unit;
FIG. 12 is an illustrative view showing a purging operation of the
maintenance unit;
FIG. 13 is an exploded perspective view showing the configuration
of an arm of the maintenance unit;
FIG. 14 is an illustrative view showing the structure of flow
channels of a nozzle head;
FIGS. 15A to 15D are illustrative views showing the operation of
the pump for the maintenance unit;
FIG. 16 is an illustrative view showing the configuration of a slip
clutch of the maintenance unit; and
FIG. 17 is an exploded perspective view showing the cassette shown
in FIGS. 5 and 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Next, the embodiment of the present invention will be described
with reference to the accompanying drawings. FIG. 1 is an overall
view showing the essential configuration of an ink-jet printer to
which the present invention is applied. The ink-jet printer of this
embodiment is a so-called hot-melt ink-jet printer, which uses ink
of a solid type and ejects the melted ink. A printer of this type
is disclosed in Japanese Patent Application Laid-open No.
5-193,152, which corresponds to U.S. Pat. No. 5,223,860 and is also
disclosed in Japanese Patent Application Laid-Open No. 8-323,999,
the disclosures of which are incorporated as a part herein by
reference. The assignee of this application has disclosed a head
structure for use in a hot-melt ink-jet printer in Japanese Patent
Application Laid-Open No. 8-305,325.
As shown in FIG. 1, a head 1 of the present ink-jet printer is
mounted in a carriage 3 (FIG. 8) so as to be movable along a guide
shaft 5. The head 1 forms an image by ejection of ink onto a
recording sheet of paper (not shown) as a recording medium,
conveyed in the central area in the movable area thereof, and moves
to a maintenance area in the vicinity of the left end (the left
side in FIG. 1) of the guide shaft 5 before and after the image
formation or at predetermined timing, whereby the head undergoes a
maintenance treatment with a roll of paper 7. Here, the carriage 3
has a well-known configuration, which is connected to a motor 8 as
the head shifting device through a belt 9, so as to move along the
guide shaft 5 in accordance with the rotation of the motor 8.
Next, the configuration of the head 1 will be described with
reference to FIGS. 2 to 4. FIG. 2 is an exploded perspective view
of the head 1, FIG. 3 is a top view of an ink tank 10 of the head
1, and FIGS. 4A and 4B are sectional views cut across lines B--B
and C--C in FIG. 3. The configuration of the head 1 is described in
detail in Japanese Patent Application No. 8-305,325.
The head 1, as shown in FIG. 2, comprises the ink tank 10, a front
panel 30, a melting tank 40, a cam 50 and a control board stage 70.
The ink tank 10 includes a front portion 15 which is inclined to
have the front panel 30 attached thereto, four sets of main
chambers 11 and sub-chambers 13 for holding four colors of hot
melted ink (which may be also referred to simply as ink) for color
output (yellow, magenta, cyan and black), an ink tank top cover 19,
and an ink tank heater 17 attached to the undersurface of the ink
tank 10. Further, as shown in FIG. 4B, each set of main chambers 11
and sub-chambers 13 in the ink tank 10 has a commutation passage 21
which opens downward, at the bottom on the rear side of the ink
tank 10.
The main chamber 11 has an L-shape configuration when viewed from
the top as shown in FIG. 2, and has a main chamber inlet 21a (FIG.
4B) that is connected to the communication passage 21, a main
chamber outlet 22a (FIG. 4A and FIG. 2) that is connected to the
front panel 30, and a filter 29 (FIG. 4A). The filter 29 is one
produced by sintering fibers of stainless steel into a sheet-like
form, and then pressing it so that fibers are complexly bent and
overlapped forming channels of a spatial structure (for example
"Tommyfilec SS" (trade name): (stainless steel sintered sheet) a
product of Tomoegawa Paper Co., Ltd.).
The sub-chamber 13 comprises a sub-chamber outlet 21b connected to
the communication passage 21, a sub-chamber inlet 22b communicating
with the front panel 30, and as shown in FIGS. 2 and 4B, an
approximately inverted T-shaped valve control lever 24 for opening
either sub-chamber outlet 21b or sub-chamber inlet 22b while
closing the other.
The valve control lever 24 is die-cast from aluminum alloy, and as
shown in FIG. 4B, is mounted so that it can be supported pivotally
at a lever seat 25 provided between the sub-chamber outlet 21b and
sub-chamber inlet 22b. The valve control lever 24 has pressure
valves 27 and 28. In this arrangement, the lever 24 is urged by a
leaf spring 26 under normal conditions so that the pressure valve
28 seals the sub-chamber inlet 22b. Here, the pressure surface of
the pressure valve 27 is of a spherical form while the socket rim
of sub-chamber outlet 21b corresponding to the valve 27 is tapered.
The pressure surface of the pressure valve 28 is flat while the
socket rim of the sub-chamber inlet 22b corresponding to the valve
28 is of an annular projected form. The pressure valves 27 and 28
are made from silicone rubber having a Shore hardness of about
40.degree. with a heat-resistance temperature of about 200.degree.
C.
The ink tank top cover 19 has, as shown in FIG. 2, a front panel
cover portion 19a which fits the shape of the front panel 30, a
sub-chamber cover portion 19b for covering sub-chambers 13, slots
19c for exposing upper ends 24a of valve control levers 24, ink
charging ports 19d through which hot-melt ink is supplied from the
melt tank 40 to the sub-chamber 13, an air chamber 20 for sending
compressed air from an aftermentioned pump 160 to each main chamber
11, a passage hole 20b on the side wall penetrating from the air
chamber 20 to the side surface of the ink tank 10, and an air
chamber lid 20a for sealing the air chamber 20. Here, the air
chamber 20 of the ink tank top cover 19 has a passage hole 23 which
is connected to each main chamber 11, as shown in FIG. 4A.
The front panel 30, as shown in FIG. 2, has four nozzle heads 31 on
the front side thereof, and the rear side of the front panel 30 is
provided with outward channels 35 (FIG. 4A) which each establish
the commutation between a corresponding main chamber 11 and nozzle
head 31, and inward channels 37 (FIG. 4B) which each establish the
commutation between a corresponding nozzle head 31 and sub-chamber
13. Further, as shown in FIG. 2 and FIGS. 4A and 4B, a cover panel
30a is provided on the rear side of the front panel 30 so as to
cover the outward and inward channels 35 and 37. Further, a front
panel heater 33 is attached to the rear side of this cover panel
30a. As shown in FIG. 4, provided at the joint from each main
chamber 11 to the corresponding outward channel 35 is an outward
entrance 35a while an outward exit 35b is provided at the joint
from the outward channel 35 to the corresponding nozzle head 31.
Further, an inward entrance 37b is provided at the joint from each
nozzle head 31 to the corresponding inward channel 37 while an
inward exit 37a is provided at the joint from the inward channel 37
to the corresponding sub-chamber 13.
The nozzle head 31 has a piezoelectric crystal-element 38, and
ejects ink supplied through the outward exit 35b, in accordance
with the change in the volume of the piezoelectric crystal-element
38. Further, ink supplied to the nozzle head 31 can be circulated
to the sub-chamber 13 by way of the inward entrance 37b and the
inward channel 37.
The cam 50 is attached over the ink tank top cover 19 so that it
can slidably move in the left and right directions in FIG. 3, with
the portion around an abutment face 50a projected to the right from
the boundary of the ink tank top cover 19. The cam 50 has four cam
surfaces 50b, and is urged by a spring 51 which is tensioned
between a projection 52 provided at the left end of the cam 50 and
a projection 19e provided in the ink tank top cover 19, so that the
cam surfaces 50b are kept out of contact with the upper ends 24a of
valve control levers 24, under normal conditions.
The melt tank 40 is partitioned into four compartments for black,
cyan, magenta and yellow, as shown in FIG. 2. Each compartment is
provided in a box-like form with a top opening so as to be charged
with solid ink. Provided the lower part of the each compartment of
the melt tank 40 is a conduit 47 for leading the molten ink to the
sub-chamber 13.
The melt tank 40 is changed with solid ink by means of an
unillustrated ink charger. The melt tank 40 has a heater, which
melts the solid ink so that the ink can be supplied to the
sub-chamber 13 of the ink tank 10 through the conduit 47. Further,
the control board stage 70 has an unillustrated control board, and
is attached to the upper part of the head 1.
In the head 1 thus configured, the control board stage 70 drives
the heaters 17, 33 etc. so as to keep the solid ink in a molten
state so that ink is ejected by driving the piezoelectric
crystal-element 38 in accordance with the print data etc., as
already mentioned. When the ink head 1 has moved to the
aforementioned maintenance area, a purging operation is performed
in the following manner. Purging is an operation of pressurizing
the ink inside the front panel 30 and the nozzle head 31 from the
main chamber side 11 to displace the ink with air bubbles and dust,
which will cause mal-ejection. More specifically, those within the
nozzle portion (designated at 31a in FIG. 14) are displaced outside
from the nozzle together with the ink while those inside the front
panel 30 are pushed into the sub-chamber 13, to thereby fill each
space with clean ink which has been filtered by the filter 29.
Contamination of the ink with air bubbles occurs when ink, which
was once molten ink but has solidified due to reduction in head
temperature after the power has been deactivated, again melts upon
re-activation of the power. As to dust, it may enter from the
nozzle.
Once the head 1 has moved to the maintenance area, the abutment
face 50a of the cam 50 is pushed against a frame 54 of the printer
body (see FIG. 3) while a hollow, cylindrical cap 55 formed in the
frame 54 covers the passage hole 20b. Then, the cam 50 relatively
slides to the left over the ink tank top cover 19, the cam surfaces
50b push respective upper ends 24a of valve control levers 24, in
the downwards direction in FIG. 3. Accordingly, each valve control
lever 24 sways pivotally at the lever seat 25, so as to release the
pressure contact between the pressure valve 28 and the sub-chamber
inlet 22b whilst a further sway establishes a pressure contact
between the pressure valve 27 and sub-chamber outlet 21b, whereby
the sub-chamber inlet 22b is opened while the sub-chamber outlet
21b is sealed.
At this moment, since the cap 55 has covered passage hole 20b,
compressed air is sent from an aftermentioned pump 160 via a pipe
57 which is connected to the hollow of the cap 55 so as to push out
air bubbles as described below. The sending of compressed air
increases the pressure inside the main chamber 11. Since the
sub-chamber outlet 21b is sealed, a positive back pressure is
applied to the ejection ink path from the main chamber 11 to the
nozzle head 31 via outward channel 35. On the other hand, since the
sub-chamber inlet 22b is open, the ink containing air bubbles from
the main chamber 11 is filtered of air bubbles and dust by the
filter 29, to reach the nozzle head 31 passing through main chamber
outlet 22a, the outward entrance 35a, the outward channel 35 and
the outward exit 35b. Then, the flow of the ink branches into two
paths, i.e., one which is discharged (ejected) to the outside from
the nozzle portion 31a and the other which is directed to the
inward entrance 37b side. The flow ratio between the two is
determined depending upon the settings of the flow resistance of
the outward channel 35, inward channel 37 and nozzle portion 31a.
The ink of the path on the inward entrance 37b side is sent to the
sub-chamber 13 by way of inward channel 37, inward exit 37a and
sub-chamber inlet 22b. Thus, the ink containing air bubbles inside
the outward channel 35, nozzle portion 31a and inward channel 37 is
replaced by clean ink.
Thereafter, the head 1 is moved to the left so as to set the
abutment face 50a away from the frame 54, whereby the upper ends
24a of the valve control levers 24 are released from being pressed
by cam surfaces 50b. At this moment, each valve control lever 24 is
moved pivotally at the lever seat 25 by the urging force of the
leaf spring 26, whereby the sub-chamber inlet 22b is sealed while
the sub-chamber outlet 21b is opened. Thereby, the ink which has
been forced to enter the sub-chamber 13 through purging is fed back
to the main chamber 11 from the communication passage 21 so that
the level of the liquid surface in the main chamber 11 can be
equalized with that in the sub-chamber 13.
When the aforementioned purging is performed, part of the ink is
forced to be ejected from the nozzle surface 36 of the nozzle head
31. In the present ink-jet printer, since the roll of paper 7 is
disposed in the maintenance area, the nozzle surface 36 is wiped by
this roll of paper 7 whilst receiving the ejected ink. Next, the
configuration of a maintenance unit 100 which feeds the roll of
paper 7 and presses it against the nozzle head 31, i.e., the
function of the maintenance mechanism, will be described. In the
beginning, since the roll of paper 7 is a consumable item, it is
held by a cassette 80 shown in FIGS. 5 and 6, and either the whole
the cassette 80 or only the roll of paper 7 is replaced when it is
used up. Distribution to the user is done either as the cassette 80
or by a set of the rolls of paper 7 for refill, which can be
selected at the user's convenience. FIG. 5 is a left-side view
showing the configuration of the cassette 80, and FIG. 6 is a
vertical sectional view of FIG. 5.
As shown in FIGS. 5 and 6, the cassette 80 is composed of a casing
82 and a cover 81 which can be pivoted at a hinge 80a in an
openable and closable manner. Provided inside the casing 82 are a
pin 83 set on the inner wall surface for supporting an unused roll
of paper 7, a fixed-rate feed roller 85 for feeding the paper from
the roll of paper 7, a winding shaft 87 for taking up the fed paper
from the roll of paper 7 and a pressing plate 89 for pressing a
stretch of paper 7 against the nozzle head 31. The side wall of the
casing 82 in which the pin 83 is formed has an approximately
U-shaped cutout to form an sectioned piece 82a. This piece 82a can
easily flex to the exterior from the casing side wall, owing to its
elasticity. Accordingly, the pin 83 can be displaced outward when a
roll of paper 7 is mounted and then case revert itself back to the
original position due to its elasticity and fit into the paper core
of the roll of paper 7, thus the roll of paper 7 is supported by
the pin 83. The rotary shaft of the fixed-rate feed roller 85 and
the winding shaft 87 are projected on the both left and right
sides, with gears 91 and 92 fixed respectively on the outside of
the left face of the casing 82.
Further, as shown in FIG. 5, formed on either side wall of the
casing 82 is a slot 82b which is approximately perpendicular to the
conveying path of the strip of paper 7 from the circumference of
the pin 83 to the fixed-rate feed roller 85. Fitted into the slots
82b is a pin 93a which is formed in a support 93 of the pressing
plate 89. The pressing plate 89 comprises this support 93, a plate
95 connected to the support 93, pivotally by a pair of pins 95a, a
compression coil spring 97 urging the plate 95 further away from
the support 93. Projected on either side of the casing 82c is a
guide pin 82c as shown in FIG. 5.
A nip roller 98 is provided inside the cover 81 mounted in
elliptical holes 81a formed in the cover 81. This nip roller 98
receives the pressure from a leaf spring 99 provided for the upper
frame of the printer body and is pressed against the fixed-rate
feed roller 85 to nip the strip of paper 7 therebetween. Further,
formed in the upper part of the cover 81 (in the upper portion in
FIGS. 5 and 6) is an opening 81b for allowing the strip of paper 7
to be projected outside and an opening 81c for allowing the
detection of the quantity of the wound roll of paper 7 on the
winding shaft 87, while an opening 82d for allowing an
aftermentioned sensor 110 to detect the presence of the roll of
paper 7 remaining on the pin 83 side is provided in the lower part
of the casing 82. There also, formed on the boundary of the opening
81b, is a notch 81d for allowing the leaf spring 99 to pass
therethrough.
Referring to FIG. 17, the cassette 80 will be described in further
detail. FIG. 17 is an exploded perspective view showing the
cassette 80 shown in FIGS. 5 and 6, with the cover 81, the pressing
plate 89, etc., removed from the cassette casing 82. The cassette
80 is assembled, as mentioned above, of the cover 81, casing 82,
fixed-rate feed roller 85, winding shaft 87, support 93, plate 95,
compression coil spring 97 and nip roller 98. Here, all the parts
except the compression coil spring 97 are molded from synthetic
resins. As examples of synthetic resin for these parts, PS
(polystyrene) is used for the cover 81 and casing 82, ABS is used
for the winding shaft 87, PC (polycarbonate) is used for the
support 93 and plate 95, POM (polyoxymethylene) is used for the nip
roller 98. Formed over the periphery of the fixed-rate feed roller
85 is an elastic layer composed of sponge, rubber or the like.
These parts can be configured so as to be disassembled into
individual parts as shown in FIG. 15, without using any tools.
Illustratively, formed on the left and right at the rear end of the
cover 81 are round bores 181 while cylindrical pins 182 projected
from the left and right inner walls are formed at the rear end of
the casing 82. The side walls of casing 82 are elastically deformed
at their rear end so that the pins 182 set on both sides fit into
respective round bores 181, forming the hinge 80a. In this way, the
cover 81 can be connected to the casing 82 in an openable and
closable manner. The cover 81 has an rectangular hole 183 at its
front end while the casing has a projection 184 at its front end.
As the cover 81 is closed with respect to the casing 82, the part
with the rectangular hole 183 is once elasticity deformed outward
and then reverts back to thereby become engaged with the projection
184. This engagement keeps the cover 81 from being opened by any
naturally arising external force.
The pins 95a of the pressing plate 89 are formed on a pair of
support tabs 95b projected from the undersurface of the plate 95.
When these support tabs 95b are elastically deformed inward and the
pins 95a are inserted into a pair of rectangular holes 93b provided
in the support 93 and revert back, the tabs 95 are connected to the
support 93, pivotally on pins 95a. In this arrangement, the
compression coil spring 97 is inserted to a hollow 93c formed on
the upper surface of the support 93, to complete the pressing plate
89. Each slot 82b in the casing 82 opens, but becomes narrowed, at
the upper edge of casing 82. This configuration allows the pressing
plate 89 to be attached to the casing 82 by squeezing the pins 93a
of the support 93 down into the slots 82b.
The fixed-rate feed roller 85 is formed integrally and coaxially
with the gear 91 and is supported rotatably by a pair of bearing
holes 82e provided in the casing 82. Each bearing hole 82e opens,
but becomes narrowed, at the upper edge of the casing 82, so as to
allow the fixed-rate feed roller 85 with gear 91 to be attached to
the casing 82 by squeezing the shaft of the fixed-rate feed roller
85 down into the bearing holes 82e. The winding shaft 87 is formed
integrally and coaxially with the gear 92 and is mounted from above
into bearing holes 82f and 82g which are formed in casing 82.
Thereafter, when the cover 81 is closed, the winding shaft 87 with
gear 92 is held between bearing hole 82f, 82 and lower edge of the
cover 81 so that it can be supported rotatably. Further, the nip
roller 98 has a flexible shaft 98a. This shaft 98a is deformed so
that both ends can be inserted into elliptical holes 81a from the
inner sides to thereby attach nip roller 98 to the cover 81.
In this way, the cassette 80 of this embodiment can be easily
assembled from, and disassembled into, individual parts without
using any tools. Accordingly, when the roll of paper 7 has been
used up from the maintenance operation, it is possible to easily
reuse the cassette 80 by refilling with a roll of paper 7 in the
following manner.
Referring next to FIGS. 7 through 9, description will be made of
the configuration of the maintenance unit 100 when the cassette 80
has been set. For simplifying the illustrations, the pressing plate
89 is omitted in FIG. 7, and the side frame 102 is depicted with
dashed line in FIG. 9. As shown in FIGS. 7 and 8, the maintenance
unit 100 has a pair of side frames 102 and 103. Each side frame 102
and 103 has guides 104 and 105, guiding the pin 82c and the winding
shaft 87, respectively (FIG. 8). When the cassette 80 is mounted
along the guides 104 and 105, movable parts 111 and 113 of the
sensor 110 disposed below those guides pivot about shafts 111a and
113a, respectively. When the cassette 80 is completely set in, the
movable part 111, on the carriage 3 side, is held inside the
cassette 80 by the pin 83 while abutting the roll of paper 7. This
sensor 110 detects the presence or absence of the roll of paper 7
based on the deflected state of the movable part 111.
Both ends of the pin 93a of the pressing plate 89 are projected
from both sides of the cassette 80, and are engaged with the distal
ends of a pair of arms 115 which can pivot about a point in the
front side (the side opposing the carriage 3: the positional
relationship of the cassette 80, i.e., the front and rear sides
thereof, will be referred to hereinbelow in the same manner) of the
maintenance unit 100. Provided at a further front position of the
maintenance unit 100 is a lever 117 which pivotally moves when the
carriage 3 abuts it. With the sway of this lever 117, the pressing
plate 89 is projected in the following way.
As shown in FIG. 7, the lever 117 is disposed pivotally about an
axle 121 which projects towards the front of the maintenance unit
100. When the carriage 3 is moved to the aforementioned maintenance
area, the lever 117 is pushed by the carriage 3 and rotated
clockwise up to a position indicated by the two-dot chain line in
FIG. 7. The lever 117 has an integrated bevel gear 117a supported
about the axle 121. This bevel gear 117a meshes another bevel gear
123a which is integrated with a pressing piece 123. This pressing
piece 123 is installed rotatably between the distal end of the axle
121 and the distal end of an axle 125 which is projected in
parallel with the axle 121. Therefore, with the above movement of
the lever 117, the pressing piece 123 rotates counterclockwise in
FIG. 8 (clockwise in FIG. 9). Here, in order to clearly depict the
configuration of the pressing piece 123, the axle 121 has been
abbreviated in FIG. 8 and the axles 121 and 125 and lever 117 have
been omitted.
As shown in FIG. 13, an iron plate 129 is connected to the front
end of paired arms 115. The distal end of the pressing piece 123
presses the iron plate 129 as it sways, as above. As shown in FIGS.
8, 9 and 13, each arm 115 includes an upper arm 131 pivoting about
an axle 115a, and a lower arm 133 which is pivotally supported
about a stepped, crimped pin 133b which is fitted into the
small-diametric part of a keyhole 131 provided in the approximate
middle of the upper arm 131. The front ends of the upper arms 131
are fixed to the left and right edges of the iron plate 129 or they
may be formed from an metal sheet and bent by folding. A helical
tension spring 135 is extended between the front end of the lower
arm 133 and the lower end of the iron plate 129. This helical
tension spring 135 urges the rear end of the lower arm 133 upwards.
The front side lower edge of the lower arm 133 abuts a projection
piece 131c formed by folding at the front side lower edge of the
upper arm 131. In this state, the rear ends of the upper arm 131
and lower arm 133 are shaped so as to create a gap 115b which can
have the pin 93a just fitted therein. The helical tension spring
135 also functions to keep the stepped, crimped pin 133b of the
lower arm 133 from moving from the small-diametric side to the
large diametric side within the keyhole 131b of the upper arm 131,
thus maintaining the mated condition.
When the iron plate 129 is pushed by the pressing piece 123, the
whole arms 115 pivot about respective axles 115a in a
counterclockwise direction in FIG. 8, so that the pressing plate 89
is projected together with a stretch of paper 7. When the pressing
plate 89 abuts the nozzle head 31 etc., with a stretch of paper 7
in between, the lower arms 133, whilst opposing the urging force of
the helical tension springs 135, pivot about respective stepped,
crimped pins 133b in a clockwise direction in FIG. 8, to thereby
reduce the impact upon abutment. Further, if any part had some
dimensional error or variation etc., due to manufacture or
assembly, or in order to improve the print quality, the distance of
the nozzle surface 36 from the platen had been modified depending
upon the type of the print paper, it is possible to urge the
pressing plate 89 uniformly against the nozzle surface 36. That is,
the pressing plate 89 corresponds to the support element for the
strip, the lever 117 corresponds to the movable element, and the
helical tension spring 135 and the lower arm 133 correspond to the
damper. Furthermore, when the pressing force from the pressing
piece 123 is not active, the arms 115 are held at the down position
by the action of a leaf spring 137 (FIG. 8).
Referring next to FIG. 9, the gear mechanism for driving the
maintenance unit 100 will be described. A gear 141 provided at the
front side of the maintenance unit 100, is disposed coaxially with
an unillustrated conveying roller for conveying a recording sheet,
and rotates as receiving the driving force from the conveying
roller. A gear 142 meshing the gear 141 has an open-V shaped lever
142a which is pivotable coaxially therewith. Attached to one end of
the lever 142a is a gear 143 meshing the gear 142, forming a
so-called planetary gear mechanism. The other end of the lever 142a
is arranged so as to be able to abut an abutment piece 131a formed
in the lower side of the upper arm 131.
The gear 141 rotates clockwise during conveyance of a recording
sheet, hence the gear 142 rotates counterclockwise while the gear
143 rotates clockwise. This causes the lever 142a to rotate
counterclockwise, so that the gear 143 is kept from meshing an
adjacent gear 144 which is integrally composed of two, large and
small-diametric gear elements. The arrows shown in FIG. 9 indicate
the movements of the gears 141 to 143 and the lever 142a in this
state. The lever 142a, when it has swayed to the position shown in
FIG. 9, will not move further due to the action of an unillustrated
stopper. Accordingly, while the head 1 is forming an image on a
sheet of recording paper as it being conveyed, no driving force is
transmitted to the maintenance unit 100.
When the conveying roller turns in the reverse direction and hence
the gear 141 is rotated counterclockwise, the lever 142a pivots
clockwise. However, if the arms 115 are in a down position as shown
by the solid line in FIG. 9, the other end of the lever 142a abuts
the abutment piece 131a of the upper arm 131. Therefore, the gear
143 will not mesh with the gear 144. When the carriage 3 has been
moved to the maintenance area by the motor 8, the lever 117 comes
into contact with the rotational carriage and rotates as stated
above so that the upper arms 131 are raised up to a position
indicated by the two-dot chain line in FIG. 9. In this state, the
conveying roller turns in the reverse direction, the lever 142a
sways to a position depicted by the two-dot chain line in FIG. 9,
and hence the gear 143 meshes the large-diametric element of the
gear 144. Briefly, only when the carriage 3 has moved to the
vicinity of the maintenance area and when the conveying roller
turns in the reverse direction, the driving force will be
transferred to the mechanism located after the gear 144.
The small-diametric element of the gear 144 meshes a gear 146 via a
large-diametric gear 145. This gear 146 has an integrated structure
having two, large and small gear elements. The gear 145 meshes the
large-diametric element of the gear 146. The unillustrated
small-diametric element of the gear 146 is configured to mesh the
gear 91 which is exposed to the outside on the left side surface of
the cassette 80, when the mounting of the cassette 80 is complete.
The large-diametric element of the gear 144 meshes a gear 149 via
gears 147 and 148. The gear 149 has two, large and small gear
elements integrated therein as shown in FIG. 10. The
small-diametric element designated at 149a is meshed with the
large-diametric gear 150. This gear 150 comes into mesh with the
gear 92 of the cassette 80 when the cassette 80 has been completely
mounted (FIG. 9). Therefore, if the driving force is transmitted to
the gear 144, the gears 91 and 92, and hence the fixed-rate feed
roller 85 and winding shaft 87 (FIG. 6), which are integrated
therewith, are caused to rotate, thus making it possible to convey
the paper from the roll of paper 7. That is, the fixed-rate feed
roller 85 and the winding shaft 87 correspond to the conveying
device.
Further, the large-diametric element 149b of the gear 149 meshes a
gear 157 which integrally rotates with a grooved cam 155. This
grooved cam 155 has two grooves 158 and 159 which are approximately
annular but eccentric, as shown in FIG. 10. These grooves 158 and
159 are to drive a pump 160. More specifically, the pump 160
comprises a piston 161 which will be slid by engagement of a pin
161a with the groove 158, and a piston 163 which will be slid by
engagement of a pin 163a with the groove 159. A cylinder 165, into
which the pistons 161 and 163 which are fitted has an intake port
165a and an exhaust port 165a formed therein.
Accordingly, as the grooved cam 155 rotates, the pistons 161 and
163 slidingly move out of phase from each other so that the volume
of the space created between the two varies. Further, since in this
case one of the ports, either the intake port 165a or exhaust port
165b is closed by piston 161 or 163, compressed air can be sent
into air chamber 20 of the head 1 via the pipe 57 (FIG. 3) from
exhaust port 165b. Therefore, when the conveying roller is reversed
after the carriage 3 has been moved to the maintenance area, it is
possible to implement the aforementioned purging whilst the roll of
paper 7 is being conveyed.
Referring next to FIGS. 11 and 12, description will be made of how
the pressing plate 89 and the roll of paper 7 operate when the
carriage 3 moves. When the carriage 3 has moved to the maintenance
area, the pressing plate 89 moves upward as stated above, and the
plate 95 is pressed against the nozzle surface 36 of the nozzle
head 31 with a stretch of paper 7 in between as shown in FIG. 11.
Provided along the upper and lower edges on the surface of the
plate 95 are a pair of ribs 95b, so that the strip of paper 7 is
tensioned between the ribs 95b. Therefore, the strip of paper 7 can
be tensioned with a remarkably good flatness over the plate 95
surface, hence is beneficially put in close contact with the nozzle
surface 36. This operation facilities wiping of pollution around
the nozzle surface 36.
Subsequently, when the conveying roller is reversed, the fixed-rate
feed roller 85 and winding shaft 87 turn as stated above to convey
the paper from the roll of paper 7. At this moment, the strip of
paper 7 is tightly nipped between the nozzle head 31 and the lower
edge of the plate 95 on the side on which the pins 95a are
provided. Accordingly, the strip of paper 7 is tensioned between
the nip and the fixed-rate feed roller 85. This tension causes the
plate 95 to rotate downward (clockwise in FIG. 11) about the pins
95a, opposing the urging force from the compression coil spring 97.
Therefore, a clearance can be formed between the nozzle surface 36
and the strip of paper 7, as shown in FIG. 12. As already stated
above, purging is performed at this moment whilst the paper is
conveyed from the roll of paper 7, thereby the formation of the
clearance facilitates a smooth ejection of ink from the nozzle
surface 36 during purging. Since the lower edge of the plate 95 is
pressed against the nozzle head 31 nipping the strip of paper 7
therebetween, the ejected ink can be beneficially received by the
roll of paper 7. Further, since the fixed-rate feed roller 85 and
the grooved cam 155 are both linked with the gear 144, the amount
of air sent from the pump 160 is in proportion to the conveyed
length of the roll of paper 7. Accordingly, the ejected amount of
ink during by purging is also in proportion to the conveyed length
of the roll of paper 7. Thus, it is possible to receive the ejected
ink in a markedly beneficial manner while also preventing the waste
of the roll of paper 7.
Then, the carriage 3 is slightly moved to the left so as to create
a gap between the passage hole 20b (FIG. 2) and the cap 55 (FIG.
3). In this situation, purging stops but the roll of paper 7 still
remains able to be conveyed. If the roll of paper 7 is kept on
being conveyed during this condition, an unused strip of paper 7
can be set over the surface of the plate 95. Thereafter, when the
carriage 3 is moved further to the left to be set away from the
lever 117 and is moved again to the maintenance area, the unused
strip of paper 7 is pressed against the nozzle surface 36 as
already stated with reference to FIG. 11. This operation
facilitates wiping of ink left over the nozzle surface 36 after
purging, to thereby complete the maintenance operation of the head
1.
Now, the operation of the pump 160 will be described in detail with
reference to FIGS. 15A to 15D. Here, FIGS. 15A to 15D are sectional
views showing the movements of pistons 161 and 163 with the
rotation of the grooved cam 155. Suppose that the state shown in
FIG. 15A represents 0.degree., FIGS. 15B, 15C and 15D show the
states where the grooved cam 155 is rotated to 120.degree.,
180.degree. and 210.degree., respectively, in the aforementioned
rotational direction (counterclockwise in FIGS. 15A to 15D)
therefrom.
FIG. 15A corresponds to a state where exhaust is complete; that is,
a space S formed between the pistons 161 and 163 is very small
while the space S opens to the exhaust port 165b. When the grooved
cam 155 turns to the position shown in FIG. 15B and hence the
pistons 161 and 163 rise with the movement, the space S opens to
the intake port 165a whereby intake is ready and can start.
Thereafter, with the piston 161 remaining at the same position, the
piston 163 goes downward so as to enlarge the volume of the space S
as shown in FIG. 15C. During this step, air is suctioned from the
intake port 165a.
When the grooved cam 155 rotates more than 180.degree., the piston
161 also starts lowering. This movement causes the piston 161 to
close the intake port 165a, then the space S is kept sealed and
moved toward the intake port 165b without varying in its volume as
shown in FIG. 15D. Since only the piston 161 moves down after the
space S has become open to the exhaust port 165b, as shown in FIG.
15A, the air within the space S is discharged through exhaust port
165b.
In this way, in the present ink-jet printer, the pump 160 is driven
by the same driving source (from the aforementioned conveying
roller integrally rotating with the gear 141, that is, from an
unillustrated motor for driving the conveying roller) as that for
the mechanism for conveying the roll of paper 7. Further, this
driving source is also shared with that for the conveying roller.
Accordingly, the maintenance unit 100 can be configured with a very
simplified design, without any its own driving source.
As stated above, in this ink-jet printer, the paper is conveyed
from the roll of paper 7 by the fixed-rate feed roller 85 and the
winding shaft 87. As the wound roll of paper 7 on the winding shaft
87 increases in radius, the conveyed length per revolution becomes
greater. Accordingly, if the winding shaft 87 is rotated at a fixed
speed during purging, the winding speed of the roll of paper 7
becomes gradually greater, so the wastage of paper 7 becomes a
maximum at the end of the roll. Particularly, in the ink-jet
printer, since the winding shaft 87 and pump 160 are driven by the
common driving source, if the windings shaft 87 and grooved cam 155
are rotated at a fixed rate, the conveyed length of the paper 7
from the roll only will increase even though the ejected amount of
ink during purging is fixed.
To overcome this problem, this ink-jet printer uses the following
two techniques so that the paper 7 will be always conveyed at a
constant rate if the grooved cam 155 rotates at a fixed speed. The
first method makes use of the aforementioned fixed-rate feed roller
85. The length to be conveyed per revolution of fixed-rate feed
roller 85 is always fixed. To achieve this, while the nip roller 98
is pressed against the fixed-rate feed roller 85 to firmly hold the
strip of paper 7 therebetween, the fixed-rate feed roller 85 is
rotated at a fixed speed to thereby convey the paper 7 at a fixed
rate from the roll.
As a second method, a so-called slip clutch (also called a torque
limiter) is provided for the driving force transmission system to
the winding shaft 87. This slip clutch is used to retard the
rotational speed of the winding shaft 87 by causing slip with
respect to the driving force transmission system when the length of
the paper 7 conveyed by the winding shaft 87 increases.
Illustratively, the small-diametric element 149a of the gear 149
which drives the winding shaft 87 via the gear 150, is configured
as follows. As shown in FIG. 16, the small-diametric element 149a,
in cooperation with a disc 491 which is integrally rotatable
therewith, but axially movable with respect thereto, holds the
large diametric element 149b therebetween via a pair of felt discs
493 interposed on both sides thereof so that the large-diametric
element 149b is rotatable relative to the other components, while a
compression coil spring 497 is disposed so as to press and hold the
element 149b. Accordingly, as the radius of the wound roll of paper
7 on the winding shaft 87 increases, the strip of paper 7 is
tensioned between the fixed-rate feed roller 85 and the peripheral
side of the winding shaft 87, this tension produces a frictional
force and causes slippage either between the small-diametric
element 149a and the felt disc 493, or the felt disc 493 and the
large-diametric element 149b. As a result, the rotational speed of
the winding shaft 87 can be adjusted to the rotational speed
associated with the conveyed length of the fixed-rate feed roller
85, thus making it possible to convey the strip of paper 7 at a
fixed rate.
As has been described above, in the ink-jet printer, the force from
the motor 8 to move the carriage 3 is utilized to move a stretch of
paper 7 toward the nozzle surface 36. Accordingly, there is no need
to provide a dedicated actuator for moving the paper 7 toward the
nozzle surface 36, thus making it possible to achieve a simplified
configuration of the maintenance unit 100. Hence, the manufacturing
cost of the ink-jet printer can also be reduced.
In the maintenance unit 100, impacts arising when the pressing
plate 89 abuts the nozzle head 31 are damped by the helical tension
spring 135 and the lower arm 133. Accordingly, the nozzle 31 can be
well protected from the impacts and it is also possible to
successfully absorb the error and fluctuations which occurred when
the arm 115 and pressing plate 89 etc. were manufactured and/or
assembled. That is, even if these elements involve such error and
fluctuations, it is possible to press the stretch of paper 7
against the nozzle head 31 at approximately constant pressure.
Further, when the distance of the nozzle surface 36 from the platen
is changed in conformity with the type of print paper in order to
improve the quality of the print, it is possible to uniformly press
the pressing plate 89 against the nozzle surface 36. Hence, it is
possible to reliably effect a markedly reliable maintenance
operation as well as to further enhance the durability of the head
1 and the productivity of the ink-jet printer.
Further, purging can be performed whilst the paper 7 is conveyed
from the roll as stated above, or the paper can be delivered from
the roll of paper 7 so that the unused part of paper may be set
over the pressing plate 89 to thereby wipe ink. Thus, the above
maintenance operation makes it possible to continuously keep the
head 1 clean. In the present ink-jet printer, it is possible to
keep the image very clear.
The conveyed length of the roll of paper 7 is maintained at a
constant in conformity with the rotational rate of the grooved cam
155, and the conveyance of the roll of paper 7 is performed in time
with the drive of the grooved cam 155. Therefore, in the
maintenance unit 100, it is possible to correctly synchronize the
conveyance of the roll of paper 7 with the drive of the pump 160
without providing any special setup. Accordingly, if the amount of
pressure from the pump 160 is varied by changing the rotational
rate of the grooved cam 155, the roll of paper 7 can be conveyed at
a rate corresponding to the amount of pressure. That is, if the
amount of pressure varies, the amount of ink ejected from the
nozzle surface 36 also varies, resulting in the length of the roll
of paper 7 required for receiving the ink to vary. In the
maintenance unit 100, since the conveyed length of the roll of
paper 7 is synchronized as stated above, it is possible to realize
a further enhanced ink reception, without needing a complex
configuration.
In the above embodiment, when the carriage 3 has not moved to the
maintenance area, the lever 142a abuts the abutment piece 131a, so
that the driving force will not be transmitted to either the pump
160, fixed-rate feed roller 85 or the winding shaft 87. That is,
while the head does not reside at the predetermined position where
the maintenance is to be implemented, a prohibiting means for
prohibiting the transmission of the driving force to the pump and
the conveying means is further provided. Therefore, it is possible
to prevent the maintenance unit 100 and thereabouts from being
polluted by a mal-operation of purging before the carriage 3 has
moved to the maintenance area, and/or prevent the roll of paper 7
from being wasted by conveyance of the roll of paper 7 whilst the
paper 7 has not been put in contact with the nozzle head 31.
The present invention should not be limited by the above
embodiments, and can be embodied in a variety of forms without
departing from the range of the invention as hereinafter claimed.
The strip may be, for example, felt etc., other than rolls of paper
7, and can be used for maintenance applications other than for
reception of ink and wiping of a nozzle surface. Here, it should be
noted that wiping of a nozzle surface includes: frictional rubbing
with the strip whilst it is abutted against the nozzle surface; and
also mere abutment of the strip against the nozzle surface. In the
above embodiment, while the strip of paper 7 is abutted against the
nozzle surface 36 to perform wiping, it is also possible to
frictionally move the nozzle surface 36 relatively with the strip
of paper 7 abutted thereto, if the following configuration is
adopted. That is, the lever 117 is configured so that when the
lever 117 rotates to a position shown by the two-dot chain line in
FIG. 7, the distal end of the lever 117 will be abutted against the
undersurface of the carriage 3 and held at that position. This
configuration enables the carriage to move left and right with the
strip of paper 7 abutted against the nozzle surface 36 to thereby
rub the nozzle surface 36 with the strip of paper 7. As for the
damper, other than, or in addition to, the above configuration
comprised of a helical tension spring 135 and a lower arm 133, an
elastic material, e.g., sponge, applied to the surface of the
pressing plate 89 may be used. This elastic material is preferably
composed of a heat-resisting material because the head will be
heated to a relatively high temperature.
Further, the pump may be a type which sucks the ink from the nozzle
surface side to thereby clean the ink ejection path. However, in
this case, it difficult to perform suctioning with the maintenance
element being abutted against the head. Therefore, in order to use
a common driving source, a planetary gear mechanism etc., may be
used to selectively transmit the driving force to the conveyer or
to the pump. Alternatively, it is also possible to provide a
configuration in which one nozzle surface adjoining to another may
be suctioned while the maintenance element may be abutted against
the other nozzle surface. In the latter case, the conveyer and the
pump can be driven simultaneously.
In the above embodiment in accordance with the first aspect of the
invention, in order to make use of the rotational force (moving
force) of the lever 117 (the moving element) rotated by the contact
with the carriage when the carriage has moved to the maintenance
area, as the driving force to cause the pressing plate 89 to move
toward the head, bevel gears 117a and 123a, the pressing pieces
123, iron plate 129 and arm 115 are used. However, these driving
force transmission elements are for illustrative purposes only, and
any power transmission elements may of course be used. That is, any
and all elements and arrangements which may occur to those skilled
in the art, as long as they can transform the moving force of the
moving element which is caused to move by the carriage into the
driving force for causing the pressing plate as the support element
to move toward the head, or can transmit the same force to cause
the pressing plate to move toward the head, should be considered to
be within the scope of the invention.
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